1. Field of the Invention
The present invention relates to a pedal crank, and more particularly to a pedal crank having a crank arm and a crank shaft that may be solidly secured together and that may include a decreased weight.
2. Description of the Prior Art
Typical pedal cranks comprise a crank shaft rotatably attached or secured in a hanger or a hub of a bicycle frame, and a pair of crank arms secured to the ends of the crank shaft with one or more fasteners, or even by forging or welding processes. Normally, one or more gear wheels or sprockets are attached or secured to the crank arms and/or the crank shaft, and thus rotated in concert with the crank arms and/or the crank shaft, and for allowing the gear wheels or sprockets to be rotated or driven by the crank arms and/or the crank shaft.
For example, U.S. Pat. No. 5,085,620 to Nagano discloses one of the typical multi-gear clusters for bicycles and also comprises one or more gear wheels or sprockets attached onto the crank arms and/or the crank shaft, for being rotated or driven by the crank arms and/or the crank shaft. However, the crank arms and/or the gear wheels or sprockets are required to be solidly secured to the crank shaft with one or more fasteners, and the fasteners are normally made of heavy metal materials and may not be removed, such that the typical multi-gear clusters may greatly increase the weight of the bicycles.
U.S. Pat. No. 5,133,695 to Kobayashi discloses another typical bicycle multiple chainwheel and also comprises one or more gear wheels or sprockets that are formed integral with the crank arms and that are solidly secured to the crank shaft with one or more fasteners, for allowing the gear wheels or sprockets and the crank shaft to be rotated or driven by the crank arms. However, the fasteners are also normally made of heavy metal materials and may not be removed, such that the typical multiple chainwheel may also greatly increase the weight of the bicycles.
In addition, it is to be noted that the structure of the conventional pedal cranks may only be made of heavy metal materials that include a heavy weight, and may not be made of other light weight materials, such as carbon fibers or glass fibers or other composite materials. For decreasing the weight of the bicycles, more and more conventional pedal cranks have been made of light weight materials, such as carbon fibers or glass fibers or other composite materials.
However, the conventional pedal cranks are normally the crank arms and/or the crank shaft and/or the gear wheels or sprockets are required to be solidly secured together with one or more fasteners, adhesive materials, or by latch pins, or by threading engagements. However, the coupling between crank arms and/or the crank shaft and/or the gear wheels or sprockets may be easily become loose after use.
The present invention has arisen to mitigate and/or obviate the afore-described disadvantages of the conventional pedal cranks for bicycles.